Bottom Line:
Indeed, these antibody-conjugated nanoparticles significantly inhibit the Aβ40 fibrillation kinetics compared with the same concentration, or even five times higher, of the free BAM10.This inhibitory effect was confirmed by different assays such as the photo-induced crosslinking of unmodified proteins combined with sodium dodecyl sulfate- polyacrylamide gel electrophoresis.A cell viability assay also confirmed that these antibody-conjugated nanoparticles significantly reduced the Aβ40-induced cytotoxicity to PC-12 cells.

ABSTRACTAmyloid-β (Aβ) peptide is the main fibrillar component of plaque deposits found in brains affected by Alzheimer's disease (AD) and is related to the pathogenesis of AD. Passive anti-Aβ immunotherapy has emerged as a promising approach for the therapy of AD, based on the administration of specific anti-Aβ monoclonal antibodies (aAβmAbs) to delay Aβ aggregation in the brain. However, the main disadvantage of this approach is the required readministration of the aAβmAbs at frequent intervals. There are only a few reports describing in vitro study for the immobilization of aAβmAbs to nanoparticles as potential targeting agents of Aβ aggregates. In this article, we report the immobilization of the aAβmAb clone BAM10 to near-infrared fluorescent maghemite nanoparticles for the inhibition of Aβ40 fibrillation kinetics and the specific detection of Aβ40 fibrils. The BAM10-conjugated iron oxide nanoparticles were well-characterized, including their immunogold labeling and cytotoxic effect on PC-12 (pheochromocytoma cell line). Indeed, these antibody-conjugated nanoparticles significantly inhibit the Aβ40 fibrillation kinetics compared with the same concentration, or even five times higher, of the free BAM10. This inhibitory effect was confirmed by different assays such as the photo-induced crosslinking of unmodified proteins combined with sodium dodecyl sulfate- polyacrylamide gel electrophoresis. A cell viability assay also confirmed that these antibody-conjugated nanoparticles significantly reduced the Aβ40-induced cytotoxicity to PC-12 cells. Furthermore, the selective labeling of the Aβ40 fibrils with the BAM10-conjugated near-infrared fluorescent iron oxide nanoparticles enabled specific detection of Aβ40 fibrils ex vivo by both magnetic resonance imaging and fluorescence imaging. This study highlights the immobilization of the aAβmAb to dual-modal nanoparticles as a potential approach for aAβmAb delivery, eliminating the issue of readministration, and contributes to the development of multifunctional agents for diagnosis and therapy of AD.

f4-ijn-8-4063: TEM images of the Aβ40 in the absence (A) and presence (B) of free BAM10 at a concentration five times higher than the conjugated BAM10 (B) 120 hours after initiation of the fibrillation process or in the presence of 50% (w/wAβ40) of the BAM10-conjugated nanoparticles dispersed in PBS, 384 (C) and 450 (D) hours after initiation of the fibrillation process.Abbreviations: TEM, transmission electron microscopy; Aβ40, amyloid-β 40; PBS, phosphate-buffered saline.

Mentions:
To assess the achieved inhibitory effect on the Aβ40 fibril formation in the presence of the BAM10-conjugated nanoparticles compared with the free × 5 BAM10, TEM images were obtained to detect morphological changes in Aβ40 solution, as shown in Figure 4. In the case of control Aβ40 solution (Figure 4A), massive networks of entangled fibrils with microsized lengths were observed after 120 hours of the fibrillation process. In contrast, when Aβ40 solution was incubated in the presence of the free ×5 BAM10 (Figure 4B), the formed fibrils after 120 hours of the fibrillation process were less massive and shorter than those observed in the control Aβ40 solution. Still, when Aβ40 solution was incubated in the presence of 50% (w/wAβ40) of the BAM10-conjugated nanoparticles (Figure 4C), even shorter fibrils were observed only after 384 hours of the fibrillation process. It is further interesting to note the selective marking of the fibrils with the BAM10-conjugated nanoparticles after 450 hours of the fibrillation process (Figure 4D).

f4-ijn-8-4063: TEM images of the Aβ40 in the absence (A) and presence (B) of free BAM10 at a concentration five times higher than the conjugated BAM10 (B) 120 hours after initiation of the fibrillation process or in the presence of 50% (w/wAβ40) of the BAM10-conjugated nanoparticles dispersed in PBS, 384 (C) and 450 (D) hours after initiation of the fibrillation process.Abbreviations: TEM, transmission electron microscopy; Aβ40, amyloid-β 40; PBS, phosphate-buffered saline.

Mentions:
To assess the achieved inhibitory effect on the Aβ40 fibril formation in the presence of the BAM10-conjugated nanoparticles compared with the free × 5 BAM10, TEM images were obtained to detect morphological changes in Aβ40 solution, as shown in Figure 4. In the case of control Aβ40 solution (Figure 4A), massive networks of entangled fibrils with microsized lengths were observed after 120 hours of the fibrillation process. In contrast, when Aβ40 solution was incubated in the presence of the free ×5 BAM10 (Figure 4B), the formed fibrils after 120 hours of the fibrillation process were less massive and shorter than those observed in the control Aβ40 solution. Still, when Aβ40 solution was incubated in the presence of 50% (w/wAβ40) of the BAM10-conjugated nanoparticles (Figure 4C), even shorter fibrils were observed only after 384 hours of the fibrillation process. It is further interesting to note the selective marking of the fibrils with the BAM10-conjugated nanoparticles after 450 hours of the fibrillation process (Figure 4D).

Bottom Line:
Indeed, these antibody-conjugated nanoparticles significantly inhibit the Aβ40 fibrillation kinetics compared with the same concentration, or even five times higher, of the free BAM10.This inhibitory effect was confirmed by different assays such as the photo-induced crosslinking of unmodified proteins combined with sodium dodecyl sulfate- polyacrylamide gel electrophoresis.A cell viability assay also confirmed that these antibody-conjugated nanoparticles significantly reduced the Aβ40-induced cytotoxicity to PC-12 cells.

ABSTRACTAmyloid-β (Aβ) peptide is the main fibrillar component of plaque deposits found in brains affected by Alzheimer's disease (AD) and is related to the pathogenesis of AD. Passive anti-Aβ immunotherapy has emerged as a promising approach for the therapy of AD, based on the administration of specific anti-Aβ monoclonal antibodies (aAβmAbs) to delay Aβ aggregation in the brain. However, the main disadvantage of this approach is the required readministration of the aAβmAbs at frequent intervals. There are only a few reports describing in vitro study for the immobilization of aAβmAbs to nanoparticles as potential targeting agents of Aβ aggregates. In this article, we report the immobilization of the aAβmAb clone BAM10 to near-infrared fluorescent maghemite nanoparticles for the inhibition of Aβ40 fibrillation kinetics and the specific detection of Aβ40 fibrils. The BAM10-conjugated iron oxide nanoparticles were well-characterized, including their immunogold labeling and cytotoxic effect on PC-12 (pheochromocytoma cell line). Indeed, these antibody-conjugated nanoparticles significantly inhibit the Aβ40 fibrillation kinetics compared with the same concentration, or even five times higher, of the free BAM10. This inhibitory effect was confirmed by different assays such as the photo-induced crosslinking of unmodified proteins combined with sodium dodecyl sulfate- polyacrylamide gel electrophoresis. A cell viability assay also confirmed that these antibody-conjugated nanoparticles significantly reduced the Aβ40-induced cytotoxicity to PC-12 cells. Furthermore, the selective labeling of the Aβ40 fibrils with the BAM10-conjugated near-infrared fluorescent iron oxide nanoparticles enabled specific detection of Aβ40 fibrils ex vivo by both magnetic resonance imaging and fluorescence imaging. This study highlights the immobilization of the aAβmAb to dual-modal nanoparticles as a potential approach for aAβmAb delivery, eliminating the issue of readministration, and contributes to the development of multifunctional agents for diagnosis and therapy of AD.